smithers

Hey guys! If anyone can help or give me some advice I'd be very appreciative. I've already dumped a lot of money into this thing and I'd like to actually figure out the issue. So anyways codes are as follows now: p0300 p0402 p1345 p0740 P0452. I know the last two have really no effect on this but figure it wouldn't hurt to give all the info. Whats been replaced: Injectors switched to MPFI (Gaskets for intake too), Plugs, Wires, Rotor, Distributer cap, coil pack, PCM, 02 Sensors(upstream). It misfires and has no power what so ever, before this issue it would smoke the back right tire off, now you have to put your foot down to get up and going. The exhaust REEKS of unburnt fuel but all of my wires are putting spark through to the plugs, the plugs have been replaced twice and are gapped correctly. Shop I took it to said cylinder 2 and 8 are the ones misfiring. This is really my winter/towing vehicle as well as hunting mule its extremely clean and has had the engine replaced ~30k on new one now 260xxx on chassis
1998 1500 5.7l Z71 Extended Cab

ChevyMan420

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ChevyMan420

change your cam sensor is underneath the roller in a distributor when you do this mark your distributor where it sets and get it right back to that. Before you hook your battery up and start the truck I had the same misfires going down the highway all the time it took me awhile and few tune ups but I figured it out. give it a shot the parts like 30 bucks takes about an hour to do it

smithers

First of all, I like the name.

I'll give the cam sensor a go tonight when I get off of work.

But I got around to messing with it last night and noticed the rotor has about .2" of play counter-clockwise, and .1-.15" play up and down. From what I understand thats really bad.

ChevyMan420

is your distributor has that much slop in it you might want to pull it out and check your gear they sometimes wear out and will cause a misfire to from what you're saying to me it sounds like it's a distributor gear or cam sensor the problem is is the slop in the distributor will cause the engine misfire. Have you checked your fuel injectors they can also cause a misfire My 97 Did the same crap ended up being one bad injector and the cam sensor so hope this helps

smithers

The injectors are the MPFI upgrade, and they all do spit out fuel, tested that when I put them it, I did a tacklebox test and put all of the injectors in a different compartment in the box and cranked it over for just a second with the ignition coil and module unplugged and every injector put out the same amount of fuel in each hole. I guess it doesn't rule out electrical components making those fire are the wrong times though.

The play with the numbers given is when the rotor is pulled up a little, I know the gears are curved on the bottom and doing that would turn it counter-clockwise, but should it not allow me to lift it up like that and give it the rotation? Otherwise when I don't pull it up and just try to turn it at its lowest position it just about a .1"

I will be pulling it out of the truck to take a good look at it, and see how the gears look a little later once I get some time. I guess with the slop in it, it wouldn't hurt to just replace the whole distributer and just see how it goes.

It does help, thank you very much sir.

Junk

I remember back in the day when this sensor went bad on my '96. I was cruising down the street and felt like Smokey from Friday, lol.

smithers

Well guys, got around to pulling the truck out of the garage and screwing around on it, and first thing I did was pull the distributer and was I suprised.